Corrosion inside frame

[limeyrob]

Just been out for a nice ride on my '59 A10, going really well but a weep from the breather.  Got down on the ground to look and noticed some corrosion on the frame bottom tube.  The more I looked the more rust streaks which I found odd as I had sanded and repainted this frame last year.  Scraped the tube and soon opened up a hole about 3/8" dia and its obvious the frame is heavily corroded inside. Started the engine and a steady stream of rust flakes fell out the frame so my conclusion is its scrap.  Pity as its a matching numbers bike.
I've never had a frame do this before, I've had the bike about 2 years and while there were signs it had been stored in a damp location, externally the frame looked fine.  Riding it and the vibration seems to have exposed the problem.
I'll be posting for a replacement frame in the wanted section and trawling e-bay.  Anyone else had this happen?

[idie]

Before scraping the frame it may be possible to cut ot the rusted part and let in a new piece.

[limeyrob]

I would be up for that but what concerns me is how widespread the cracks in the paint are and rust streaks.  This is a frame that was painted about a year ago and showed nothing so I'm thinking the internal corrosion is widespread.  Its also under the side stand bracket.

[idie]

If it were mine I would try to find a damaged frame.I would get some spigots made and remove some of the frame and fit in another piece. A B series frame would do as a donor as well.

[Gup holland]

Seen a lot coroded frames, but not like this

[limeyrob]

Me neither!

[iansoady]

At least you found it before it collapsed under you!

[DAVE BRADY]

Hi,

Is this a clamp on stand?  I think I can make out the remains of sleeve for a brazed side stand lug.
As standard, half of the clamp was attached to the frame and if the clamp became loose it could wear through the frame.

Dave.

[limeyrob]

I got underneath after the ride to look for the oil leak.  When i wiped the frame I noticed the paint was lifting in many places. At first I thought stone chips but each one was coming though from inside, that hole is the one I dug into but there were many over the whole length on the bottom tubes. I ran the engine to monitor the breather (it is breathing too hard, that's another story) and a steady stream of rust flakes fell out the hole and made a little pile.
I'm sure the frame is toast but I've been riding BSA's a since 1971 and I never seen anything like this.

[EDDIE SIMPSON]

it used to be common on cb750 frames, the bottom rails had 1/8 drain holes that clog up and cause internal corrosion. its a red ticket mot failure as any light prang could be a disaster.

[limeyrob]

While clearing the work space to strip the bike I remembered the only time I'd seen corrosion like this was a car that had been by the coast all its life.  Surface paint was fine but all the body was paper thin and corroded from inside.  That got me thinking and the bike came with the buff log book:
Plymouth
Plymouth
Plymouth
Plymouth
Headcorn
Forfar
Montrose
Dundee
So its spent most of its life by the sea. Well at least that explains it.  I think the condensation is salty and the air is always damp.

[limeyrob]

Got the frame off (or rest of bike off frame...) here's what its like underneath.

[DAVE BRADY]

Hi,

Is the other side the same?

Dave.

[iansoady]

I wouldn't put my trust in anything from that frame.

[limeyrob]

I don't trust it.  It does appear to be only on one side but there is evidence near where the side loop joins the top tube. OK its the same side but its high up.  Thing is I sanded and sprayed this frame about 12 months ago and this wasn't visible.  I'll cut it up when I get time, I'll need to keep the head-stock and number for when I negotiate with the DVLA at some stage.  Its a decent bike and nice to ride so I'm looking for a good frame.